Massachusetts General Hospital has been in the forefront of PET instrumentation development for decades. The demonstration device, PCR-I, constructed in 1983 has been in effective use since then. Now, however, natural corrosion and wear has depredated the imaging characteristics and the performance of the old instrument to the level, that it is not suitable to carry on the PET imaging studies in many research programs developed around it. PCR-I has been used for a number of different types of animal studies, like studies of glucose metabolism in nude mice or stroke rat model, receptor studies of dopaminergic function in rat and primate brain, gated studies of glucose metabolism and blood flow in ischemic and infarcted dog heart, and others. The resolution of the PCR-I has been 4.5 mm with sensitivity of 46kHz/mu Ci. To carry on the ongoing research projects and prepare for future challenges a new imaging instrument to replace PCR-I is of extreme importance. For the ongoing applications especially for studies of multitarget transplantation in primate brain including areas of putamen, subthalamic nucleus and substantia nigra, a high resolution imaging device is needed. Concorde Microsystems Incorporated has offered a primate microPET system, which can be for these applications. The resolution is 2 x 2 x 2 mm in the target and absolute sensitivity is 500Hz/mu Ci. PCR-I is a single ring device, while the microPET system has a volumetric data acquisition with axial length of 8 cm, so dynamic data collection can be done over the whole primate brain. This enables 10-15 fold more data points and better temporal resolution for the time-activity curves, and further enables rigorous modeling to resolve statistically meaningful physiological parameters. This shared instrumentation grant is submitted to enable us to replace an aging and unreliable animal PET instrument with a state of art commercial PET system. This will enable us to continue and expand our PET imaging facility and to improve the quality of the PET images. Our previous experience in developing and operating PET systems will be of great benefit in the expansion of the facility.